Disconnection syndrome

From Wikipedia, the free encyclopedia
Diffusion tensor imaging of the brain showing the right and left arcuate fasciculus (Raf & Laf), the right and left superior longitudinal fasciculus (Rslf & Lslf), and tapetum of corpus callosum (Ta).

Disconnection syndrome is a general term for a number of neurological symptoms caused by damage to the white matter axons of communication pathways—via lesions to association fibers or commissural fibers—in the cerebrum, independent of any lesions to the cortex.[1] The behavioral effects of such disconnections are relatively predictable in adults.[2]

Callosal syndrome, or split-brain, is an example of a disconnection syndrome from damage to the corpus callosum between the two hemispheres of the brain. Disconnection syndrome can also lead to aphasia, left-sided apraxia, and tactile aphasia, among other symptoms.

History

The concept of disconnection syndrome emerged in the late nineteenth century when scientists became aware that certain neurological disorders result from communication problems among brain areas.[3] In 1874, Carl Wernicke introduced this concept in his dissertation when he suggested that conduction aphasia could result from the disconnection of the sensory speech zone from the motor speech area by a single lesion in the left hemisphere[2] to the arcuate fasciculus.

Lissauer, a pupil of Wernicke, described a case of visual agnosia as a disconnection between the visual and language areas.[4]

Dejerine in 1892 described specific symptoms resulting from a lesion to the corpus callosum that caused alexia without agraphia. The patient had a lesion in the left occipital lobe, blocking sight in the right visual field (hemianopia), and in the splenium of the corpus callosum. Dejerine interpreted this case as a disconnection of the speech area in the left hemisphere from the right visual cortex.

Commissural disconnect

Commissural disconnection syndrome in adults usually results from surgical intervention, tumor, or interruption of the blood supply to the corpus callosum or the immediately adjacent structures.

Callosal disconnection syndrome is characterized by left ideomotor apraxia and left-hand agraphia and/or tactile anomia, and is relatively rare.[5]

Association pathway disconnect

Disconnection syndromes from lesions in other association pathways have not been studied as extensively as the callosal syndrome.

See also

References

  1. ↑ David Myland Kaufman (2007). Clinical Neurology for Psychiatrists. Elsevier Health Sciences. pp. 171–. ISBN 978-1-4160-3074-4. Retrieved 4 August 2013. 
  2. ↑ 2.0 2.1 Otfried Spreen; Anthony H. Risser; Dorothy Edgell (1995). Developmental Neuropsychology. Oxford University Press. pp. 156–. ISBN 978-0-19-506737-8. Retrieved 4 August 2013. 
  3. ↑ Dr. Robert Melillo (6 January 2009). Disconnected Kids: The Groundbreaking Brain Balance Program for Children with Autism, ADHD, Dyslexia, and Other Neurological Disorders. Penguin Group US. pp. 14–. ISBN 978-1-101-01481-3. Retrieved 4 August 2013. 
  4. ↑ Daria Riva, Charles Njiokiktjien, Sara Bulgheroni (1 January 2011). Brain Lesion Localization and developmental Functions : Frontal lobes, Limbic system, Visuocognitive system. John Libbey Eurotext. pp. 3–. ISBN 978-2-7420-0825-4. Retrieved 4 August 2013. 
  5. ↑ Stroke: Clinical manifestations and pathogenesis. Elsevier Health Sciences. 2009. pp. 429–. ISBN 978-0-444-52004-3. Retrieved 4 August 2013. 
This article is issued from Wikipedia. The text is available under the Creative Commons Attribution/Share Alike; additional terms may apply for the media files.